Disposable absorbent products have met with widespread acceptance in the marketplace for a variety of applications, including infant and adult incontinence care, in view of the manner in which such products can provide effective and convenient liquid absorption and retention while maintaining a reasonable level of comfort for the wearer. However, a need exists for backsheet materials that can provide a level of air permeability more like that of a woven textile fabric of conventional clothing, while maintaining sufficient liquid barrier performance for its intended use. Absorbent products with an air permeable backsheet can provide increased comfort for the wearer by helping to maintain the natural transpiration of the skin to reduce heating and sweating of occluded sections of the body. So-called “breathable” backsheet films that are currently used in the hygiene industry allow for a slow diffusion of water molecules through them but provide negligible air permeability.
Liquid barrier performance of fabric and nonwovens adequate for certain end uses can be achieved with fibers that have advancing water contact angles of less than 90° if the nonwoven is comprised of small enough pores. For example, the meltblown component of a Spunbond-Meltblown-Spunbond (SMS) polypropylene nonwoven provides the small pores required to improve liquid barrier performance for leg gathers in a baby diaper. While the pores are small enough to provide some liquid barrier performance, they are still large enough to maintain a high level of air permeability. Recent attempts to further improve the liquid barrier performance of nonwovens, and to reduce the basis weight of the nonwoven required for performance, has focused on making the nonwovens with finer fibers that can generate even smaller pore size distributions. For example, U.S. Pat. No. 5,885,909, hereby incorporated by reference, teaches the use of sub-denier fibers for nonwoven structures to achieve high hydrostatic head with high air permeability. Another example, U.S. Pat. No. 7,195,621, hereby incorporated by reference, uses a meltblown nonwoven backsheet for a disposable garment to enhance breathability.
U.S. Patent Application Publication US 2005/0245159, hereby incorporated by reference, discloses a breathable barrier composite comprising a compressed mat of airlaid hydrophobic cellulose fibers and thermally-bonded polyolefin fibers. However, it is not possible to generate a uniform distribution of small enough pores with this type of a fiber composite.